 In the meantime, Kertanegara had dominated all of Java, but before the Mongol fleet arrived, a dramatic political change occurred.Jayakatwang, prince of Kediri and one of Singhasari's most powerful vassals, rebelled against his overlord.With the bulk of the Javanese army in campaign overseas and Singasari's defence weakened, Jayakatwang seized his chance and launched a coup against Kertanegara.